Footing Size Calculator
Determine the required footing area and side length based on column load and soil bearing capacity.
How to Use the Footing Size Calculator
- Enter the column load in kilonewtons.
- Enter the allowable soil bearing capacity in kPa.
- Click Calculate to get the required footing area and side length.
Use Cases
- •Sizing isolated spread footings.
- •Preliminary foundation design.
- •Checking adequacy of existing footings.
- •Structural engineering coursework.
Formula
A = P / q, where P is the column load (kN) and q is the soil bearing capacity (kPa). Footing side = √A.
Frequently Asked Questions
What is a footing?
A footing is a structural element that transfers column or wall loads to the underlying soil.
What is soil bearing capacity?
It is the maximum pressure the soil can support without shear failure or excessive settlement.
Should I add a safety factor?
Yes — the bearing capacity entered should already be the allowable (design) value, not the ultimate value.